Fix spew when running presubmit which triggers dartfmt.bat on windows. We should also backport this…

sdk/bin/dart2js.bat

 @echo off
 REM Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 REM for details. All rights reserved. Use of this source code is governed by a
 REM BSD-style license that can be found in the LICENSE file.
 
 setlocal
 rem Handle the case where dart-sdk/bin has been symlinked to.
 set DIR_NAME_WITH_SLASH=%~dp0
 set DIR_NAME=%DIR_NAME_WITH_SLASH:~0,-1%%
 call :follow_links "%DIR_NAME%", RETURNED_BIN_DIR
@@ skipping 32 matching lines @@
 
 endlocal
 
 exit /b %errorlevel%
 
 :follow_links
 setlocal
 for %%i in (%1) do set result=%%~fi
 set current=
 for /f "usebackq tokens=2 delims=[]" %%i in (`dir /a:l "%~dp1" 2^>nul ^
-                                             ^| %SystemRoot%\System32\find.exe ">     %~n1 ["`) do (
+                                             ^| %SystemRoot%\System32\find.exe ">     %~n1 [" 2^>nul`) do (
   set current=%%i
 )
 if not "%current%"=="" call :follow_links "%current%", result
 endlocal & set %~2=%result%
 goto :eof
 
 :end